Some common materials used for heavy type banded fittings include:
Carbon Steel
One of the most common materials. Provides good tensile strength and is relatively inexpensive. Typically used in low pressure applications.
Stainless Steel
More expensive but provides very good corrosion resistance. Often used for higher pressure applications or highly corrosive environments. Grades 304 and 316 are common.
Cast Iron
Traditionally used material that is very rugged but brittle. Typically only used for low pressure fittings.
Ductile Iron
Excellent tensile properties and less brittle than standard cast iron. Used for both low and medium pressure applications.
Alloy Steel
Used when high strength is needed. Grades such as 4140 and 4340 are typical. More expensive than carbon steel.
Nickel Alloys
Excellent corrosion resistance. Often used in highly corrosive chemical and petrochemical processing environments. Examples are Alloy 20, Alloy C-276, and Monel.
Non-metallic
Fiberglass and reinforced thermoset plastic materials can be used as liners in steel or alloy housings. Provides corrosion allowance.
The specific material used depends on the service conditions such as pressure, temperature, chemicals present, and cost considerations. Manufacturers select the optimal materials for the intended application.